We have the option of having different merchant accounts because each account has specific settings.  You may want one that has stricter security for CSC numbers (3 digits on the back of a credit card) or AVS (address verification service).  Also, some customers have multiple gateways they use - IATS, BBMS, Cybersource - and would need separate merchant accounts.  Lastly, you may want to set up a merchant account in ‘Test’ or ‘Demo’ mode to do some testing without tampering with your live production merchant accounts (e.g. test a new page or batch process without having to change your live NetSolutions merchant account to Test or Demo).